Neural interactions between motor cortical hemispheres during bimanual and unimanual arm movements

Cortico-cortical connections through the corpus callosum are a major candidate for mediating bimanual coordination. However, aside from the deficits observed after lesioning this connection, little positive evidence indicates its function in bimanual tasks. In order to address this issue, we simultaneously recorded neuronal activity at multiple sites within the arm area of motor cortex in both hemispheres of awake primates performing different bimanual and unimanual movements. By employing an adapted form of the joint peri-stimulus time histogram technique, we discovered rapid movement-related correlation changes between the local field potentials (LFPs) of the two hemispheres that escaped detection by time-averaged cross-correlation methods. The frequency and amplitude of dynamic modifications in correlations between the hemispheres were similar to those within the same hemisphere. As in previous EEG studies, we found that, on average, correlation decreased during movements. However, a subset of recording site pairs did show transiently increased correlations around movement onset (57% of all pairs and conditions in monkey G, 39% in monkey P). In interhemispheric pairs, these increases were consistently related to the mode of coupling between the two arms. Both the correlations between the movements themselves and the interhemispheric LFP correlation increases were strongest during bimanual symmetric movements, and weaker during bimanual asymmetric and unimanual movements. Increased correlations occurred mainly around movement onset, whilst decreases in correlation dominated during movement execution. The task-specific way in which interhemispheric correlations are modulated is compatible with the notion that interactions between the hemispheres contribute to behavioural coupling between the arms.     

A Doubly Fmoc-Protected Aspartic Acid Self-Assembles into Hydrogels Suitable for Bone Tissue Engineering

Hydrogels have been used as scaffolds for biomineralization in tissue engineering and regenerative medicine for the repair and treatment of many tissue types. In the present work, we studied an amino acid-based material that is attached to protecting groups and self-assembles into biocompatible and stable nanostructures that are suitable for tissue engineering applications. Specifically, the doubly protected aspartic residue (Asp) with fluorenyl methoxycarbonyl (Fmoc) protecting groups have been shown to lead to the formation of well-ordered fibrous structures. Many amino acids and small peptides which are modified with protecting groups display relatively fast self-assembly and exhibit remarkable physicochemical properties leading to three-dimensional (3D) networks, the trapping of solvent molecules, and forming hydrogels. In this study, the self-assembling fibrous structures are targeted toward calcium binding and act as nucleation points for the binding of the available phosphate groups. The cell viability, proliferation, and osteogenic differentiation of pre-osteoblastic cells cultured on the formed hydrogel under various conditions demonstrate that hydrogel formation in CaCl₂ and CaCl₂-Na₂HPO₄ solutions lead to calcium ion binding onto the hydrogels and enrichment with phosphate groups, respectively, rendering these mechanically stable hydrogels osteoinductive scaffolds for bone tissue engineering.     

Effects of ketogenic diet and ketone bodies on the cardiovascular system: Concentration matters

Ketone bodies have emerged as central mediators of metabolic health, and multiple beneficial effects of a ketogenic diet, impacting metabolism, neuronal pathologies and, to a certain extent, tumorigenesis, have been reported both in animal models and clinical research. Ketone bodies, endogenously produced by the liver, act pleiotropically as metabolic intermediates, signaling molecules, and epigenetic modifiers. The endothelium and the vascular system are central regulators of the organism’s metabolic state and become dysfunctional in cardiovascular disease, atherosclerosis, and diabetic micro- and macrovascular complications. As physiological circulating ketone bodies can attain millimolar concentrations, the endothelium is the first-line cell lineage exposed to them. While in diabetic ketoacidosis high ketone body concentrations are detrimental to the vasculature, recent research revealed that ketone bodies in the low millimolar range may exert beneficial effects on endothelial cell (EC) functioning by modulating the EC inflammatory status, senescence, and metabolism. Here, we review the long-held evidence of detrimental cardiovascular effects of ketoacidosis as well as the more recent evidence for a positive impact of ketone bodies—at lower concentrations—on the ECs metabolism and vascular physiology and the subjacent cellular and molecular mechanisms. We also explore arising controversies in the field and discuss the importance of ketone body concentrations in relation to their effects. At low concentration, endogenously produced ketone bodies upon uptake of a ketogenic diet or supplemented ketone bodies (or their precursors) may prove beneficial to ameliorate endothelial function and, consequently, pathologies in which endothelial damage occurs.